Subject: [PATCH] powerpc/pseries: Disable VPNH feature

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 10 Mar 2011 10:00:14 +1100

This feature triggers nasty races in the scheduler between the
rebuilding of the topology and the load balancing code, causing
the machine to hang.

Disable it for now until the races are fixed.

Signed-off-by: Benjamin Herrenschmidt <[email-masked]>
---

Jesse: I'm sending that to Linus now. We'll sort things out for the
next release.

diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index fd48123..74f1baa 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1516,6 +1516,7 @@ int start_topology_update(void)
 {
 	int rc = 0;
 
+#if 0 /* Disabled until races with load balancing are fixed */
 	if (firmware_has_feature(FW_FEATURE_VPHN) &&
 	    get_lppaca()->shared_proc) {
 		vphn_enabled = 1;
@@ -1524,6 +1525,7 @@ int start_topology_update(void)
 		set_topology_timer();
 		rc = 1;
 	}
+#endif
 
 	return rc;
 }